The invention relates to open cell foamed articles.
Open cell foams emulate the open or interconnected cell structure of the a marine sea sponge. Open cell foams can be used in many different applications. Open cell foams made from polymer resins can be flexible and elastomeric. In contrast, brittle open cell foams can be made from ceramic or glass structures.
The open cell structure permits the flow of a liquid or gas medium through the interconnecting cellular structure of the foam without destroying the foam structure. The liquid can be, for example, water or oil, or the gas can be air or nitrogen. The characteristics of a foam can be modified for specific applications. For example, the foam can act as an absorbent for a specific liquid (e.g., as a sponge). Open cell foams can act as a filtering mechanism, permitting the flow of a liquid or gas through the structure while separating out materials from that flow and retaining the materials in the foam structure. It is possible to impregnate the structure with an additive which can later be mechanically squeezed out for application onto another surface. Open cell foams can also be used in cushioning applications.
Synthetic materials have been developed for producing flexible open cell foams. Natural rubber latex foams provide soft materials for body contact and the application of cosmetics. Polyvinyl chloride (PVC) plastisol foams can have a soft, durable feel that simulates leather to the touch. Open cell foams based on polyurethanes have been made suitable for many applications, such as cushions for packaging, automotive applications, home bedding, filters (e.g., for air conditioners), applicators (e.g., for shoe polish), or sound attenuating panels (e.g., for rooms or speakers). Open cell foams based on ethyl vinyl acetate (EVA) can be made in a melt process to lower foam densities than earlier foams. The EVA-based foams have a high percentage of non-interconnecting cells yielding a primarily open cell foam. The EVA-based open cell foams can be soft and pliable.